This invention relates to a metallic amalgam and method of combining an alkali metal and aluminum by using mercury as an amalgamation medium.
Recently I discovered a use for an amalgam of alkali metal and aluminum with an atomic weight ratio of alkali metal to mercury from about 100:1 to about 1:100 and the atomic weight ratio of alkali metal to aluminum from about 1:100 to about 100:1. Preferably, the amalgam used has an atomic weight ratio of alkali metal to mercury from about 3:1 to about 1:1.5 and the atomic weight ratio of alkali metal to aluminum from about 1:1 to about 3:1.
I further found that although it is well known in the prior art to combine alkali metals with mercury into an amalgam, providing an amalgam of alkali metal and aluminum either in a direct combination using a high temperature phase or in an indirect combination by using mercury as an amalgamation medium is not known.
The method I have found which enables production of an amalgam of alkali metal and aluminum comprises the steps of making an alkali metal amalgam under an inert atmosphere. The surface of aluminum is then coated with mercury and the coated aluminum is mixed with the alkali metal amalgam and given sufficient time to form the amalgam of alkali metal and aluminum.
It is important to remember that this method is carried out under an inert atmosphere, such as helium or argon, so as to prohibit the formation of hydroxide contaminants on the surface of the alkali metal and oxide contaminants on the surface of the alkali metal and aluminum.
Further, it is important that the surface of the aluminum be treated to remove aluminum oxide so as to enable coating the aluminum with mercury. This may be accomplished by mechanically working the aluminum, such as with a ball mill, or by immersing the aluminum in an aqueous mercuric chloride solution, preferably a saturated aqueous mercuric chloride solution, so as to deposit a coating of mercury over the aluminum, either being in particles, sheets or whatever mass form desired. The aluminum is then left in the mercuric chloride solution for a sufficient period of time to chemically replace the oxygen in the aluminum oxide with mercury. A sufficient quantity of mercury is then added to the aqueous mercuric chloride solution to thereby immerse the surface treated aluminum in the mercury and rapidly displace the mercuric chloride solution to prevent the continued contact of water in the solution with the coated aluminum. The mercuric chloride solution may then be removed by any of the well known methods for liquid removal from the surface of the mercury. The atmosphere is then purged to remove any and all moisture and oxygen. The coated aluminum and a measured amount of mercury are provided so as to make the amalgam described in application Ser. Nos. 902,705, 902,708 and 06/068,749, the information therein being incorporated herein by reference.
The mixture may then be allowed to combine in a natural fashion or this amalgamation may be facilitated by utilizing an elevated temperature, preferably around 200.degree. C..+-.10.degree. C. The amalgam is preferably maintained at this elevated temperature for about 10 minutes for the first 100 grams being processed and the time extended about 1 minute for each additional 100 grams thereafter.
The resulting amalgam is then cooled gradually to room temperature under an inert atmosphere. For this purpose, either helium or nitrogen are satisfactory and it is desirable that cooling be effected in a desiccator to ensure that no water contacts the amalgam.